Castor Bean


R. communis

Derivation of the Name Castor

Castor is the generic name of the North American beaver (Castor canadensis) and one of the brightest double stars in the constellation Gemini. In Greek and Roman legend, Castor was one of the twin sons of Jupiter and Leda. According to E. A. Weiss, writing in Castor, Sesame and Safflower (1971), the name "castor" has nothing to do with beavers, luminous stars, or offspring of Greek and Roman Gods. Castor was apparently coined by English traders who confused it with the oil of another shrub, Vitex agnus-castus, which the Spanish and Portuguese in Jamaica called "agno-casto." Although it is commonly known as the castor bean plant, the seed is really not a true bean and it is not related to the Bean or Legume Family (Fabaceae). There are many other examples of "beans" that are technically not beans, such as Mexican Jumping "beans" and coffee "beans."

Common names
Castor Bean, Castor Oil Plant, Palma Christi

The castorbean plant (Ricinus communis) has been cultivated for centuries for the oil produced by its seeds. The Egyptians burned castor oil in their lamps more than 4,000 years ago. In the 1920's Mussolini's thugs used to round up dissidents and pour castor oil down thier throats as a way of torcher. (Stewart, Amy. Wicked Plants. Workman Publishing, NY 2009.)


The Spurge Family
Rubber, poinsettias, manioc and castor oil all come from the Euphorbiaceae family. The only species occurring naturally in the mountaneous Northwest are herbaceous weeds, but most members of the family are shrubs or trees. Species of the family nearly always have alternate, stipulate, simple leaves, although a few have palmately compound leaves. All members of the family have separate male and female flowers that grow either on the same plant or on separate plants. Most species have 5 flower segments. In Euphorbia, what appears as a flower at first glance is, in reality, a part of a flower cluster. There are 5 individual stamens or 5 clusters of stamens. These are attached to small stalks that are, in turn, attached to the inside of the cyathium. Each fascicle is an individual staminate flower. There is only one pistillate flower in each cyathium. It is a pretty minimal flower, consisting of a single pistil on a short stalk. As in all members of the family, the pistil is 3-celled. The seeds often have a swelling that is rich in oils.

The plant is thought to be native to tropical Africa. The seeds, leaves, and stems of the plant contain ricin and ricinine, which are poisonous to humans and animals. Eating a castorbean causes nausea, and eating several may cause death. These toxic compounds are not present in the oil. Castorbeans are grown on a limited scale in the United States. The castorbean plant grows well in soil of medium texture. It is best adapted to southeastern Kansas, Missouri, southern Illinois, southern Indiana, Tennessee, Kentucky, and parts of Oklahoma and Texas. With irrigation, it also grows well in the Southwest.
In the United States, castor oil has been used by the military in aircraft lubricants, hydraulic fluids, and in the manufacture of explosives. It has also been used in the synthesis of soaps, linoleum, printer's ink, nylon, varnishes, enamels, paints, and electrical insulations. Textile scientists have used sulphonated castor oil in the dyeing and finishing of fabrics and leather. The most infamous application of castor oil may have been as a purgative popular for the treatment or prevention of many ailments in the first half of the twentieth century.
Castorbean meal is included as a protein source in feed for swine. Castorbean pomace, or meal, the residue left after the oil has been extracted from the seeds, has been included in mixed fertilizer.


Wild Card
Lesson Plan: Castor Beans

Grade Level: 9-12

In this lesson plan students will investigate the Castor Bean plant and how castor bean consumption affects humans.

Students will research Castor Beans and how they can be deadly.
Students will create a brochure; similar to one found at a doctor’s office, that describes the plant and how the plant affects the human digestive system, its causes, symptoms, and possible treatments

Paper (81/2 x 11 inches)
Pens, pencils
Computer with Internet access

  1. Begin the lesson by reviewing the major organs of the digestive system and the function of each as a power point presentation.
  2. Ask students to work in cooperative groups to investigate Castor Beans and the human digestive system.
  3. Have criteria and rubrics for students prior to lesson. Have the students work individually to create a brochure about how the plant and how it would affect the human body if ingested. Describe the problem, symptoms, and possible treatments. In addition, the brochure should be written and designed for a specific audience, such as kids, teens, young adults, or older people. Each brochure should include age appropriate illustrations and/or diagrams to help explain the problem and describe the plant.
  4. Have students create their brochures by folding an 81/2 by 11-inch piece of paper intro thirds. They may also use a Microsoft Word program. Remind students to include images with labels, whether they import them from another file or sketch them by hand.
  5. When the brochures are compete, have students work with their groups to explain the brochures.

The teacher will use a rubric to evaluate students’ work.

Stewart, Amy. Wicked Plants. Workman Publishing, NY 2009.